A portion of the semiconductor device manufacturing process involves the processes of mounting and dicing a semiconductor wafer into singulated components. Typically, the wafer includes a plurality of semiconductor dice or semiconductor packages (“dice”). One technique for dicing a wafer is saw cutting. With saw cutting, the wafer is mounted to a support member, and a diamond tipped saw rotating at high speed saws the wafer along pre-formed lines known as streets.
A typical support member for dicing a wafer is known as a film frame. The film frame includes a metal frame, and an adhesive dicing tape stretched across the metal frame. The dicing tape is typically a polymer film having an adhesive layer of approximately 10 microns on at least one side. The dicing tape is formulated to provide a high adhesion with the wafer in order to prevent the wafer, and the singulated components, from moving during the dicing process.
The high adhesion of the dicing tape is also advantageous for transporting the singulated components on the film frame for further processing, such as packaging. However, the high adhesion of the dicing tape is a disadvantage when the singulated components must be removed from the tape. For example, mechanisms, such as pushers and vacuum picks, are utilized to either push or pull the singulated components from the dicing tape. These mechanisms are hampered by the high adhesion of the dicing tape, which must be overcome to separate the singulated components from the tape.
This problem can be addressed through the use of a dicing tape having an adhesive that is sensitive to a radiation, such as ultraviolet radiation. With a radiation sensitive dicing tape, exposure of the backside of the tape to the radiation reduces the adhesion of the tape, allowing the singulated components to be more easily separated from the tape. Typically, the entire backside of the dicing tape is exposed to the radiation, and adhesion of the tape can be significantly reduced.
The dicing tape is applied to the wafer and pressed against the wafer by a roller that applies pressure to the dicing tape and the wafer. Typically, the dicing tape will be rolled onto the backside of the wafer. This is because the frontside of the wafer may have bump electrodes (bumps), which would provide less contact area for the dicing tape. Moreover, the bump electrodes on the frontside of the wafer could be damaged by the pressure from the roller.
Recently, to facilitate wafer stacking schemes, wafers having bumps on both sides have been developed. Such wafers present problems in regard to typical dicing tape application procedures. For example, the wafers are typically very thin (approximately 150 microns). This is because the bumps on each side are typically connected through vias in the wafer. The vias may be formed by chemical drilling. The wafers may be thinned to better effect such chemical drilling and to maintain a small stack height. Such thin and fragile wafers can be easily damaged during the mounting and dicing process and the resultant thin die, when singulated, may not adhere well to the dicing tape.
Additionally, the bumps on at least one side of the wafer may be made of lead, a lead/tin alloy, or some other low melting point metal, to allow bonding to another wafer through a bump reflow process. Such metals are relatively soft compared to copper, which is typically used for bumps on a one-sided bumped wafer. Such soft metal bumps are more susceptible to deformation during the mounting and dicing process.